The connections of the vestibular nuclei will be studied in the cat using both anterograde and retrograde techniques. The anterograde techniques will utilize the Nauta silver method to demonstrate axonal degeneration following small non-electrolytic lesions made under direct visual control in the cerebellum and brainstem. Projections to be studied intensively with this method will be: cerebello-vestibular connections, connections of associated small vestibular nuclei (Group Y), descending projections of the vestibular nuclei, and other nearby nuclei of the vagus nerve. The retrograde method is based on the localization of protein tracers (such as horseradish peroxidase) to demonstrate retrograde protein transport following injection of the tracer near the ending or endplate of efferent neurons. This method will be employed to study the origin of ascending and descending efferent projections of the major vestibular nuclei.